Predicting the number of nymphal instars plus new-generation adults of the Sunn Pest from overwintered adult densities and parasitism rates

摘要

The present study evaluated the effect of overwintered adult density and egg and adult parasitism rates on the new-generation population densities of the Sunn Pest {Eurygaster integriceps Put.) under field conditions. We quantified the abundance of overwintered adult densities and egg and adult parasitism rates in 20 one-ha unsprayed wheat fields in southeastern Turkey to assess their impact on nymphal instars, plus new-generation adult densities. The number of overwintered adults per square meter and the percent of egg parasitism rates were positively and negatively correlated with new-generation densities of the Sunn Pest, respectively. The results of multiple regression analysis produced the equation Y= 15.037 + 8.287 OW (overwintered adult) — 0.235 egg PR (parasitism rate). The findings suggest that the egg parasitoids may suppress nymphal instars plus new-generation adult densities of the Sunn Pest. The findings also suggest that the present formula can be used to determine the spraying areasin which densities reach economic threshold for the integrated Sunn Pest management program in wheat fields in Turkey.